Gas turbines, such as, for example, aircraft engines, include, as a rule, a plurality of rotating rotor blades as well as a plurality of stationary stator blades, the rotor blades rotating together with a rotor, and the rotor blades as well as the stator blades being enclosed by a stationary housing of the gas turbine. It may be provided to optimize all components and subsystems when it comes to improving the performance of an aircraft engine. Among those are also the so-called sealing systems in aircraft engines. In aircraft engines, a particular problem is keeping a minimum gap between the rotating rotor blades and the stationary housing of a high pressure compressor. The highest absolute temperatures and temperature gradients occur in high pressure compressors, and this makes maintaining the gap of the rotating rotor blades from the stationary housing of the compressor more difficult. Among other things, this is also because in the case of compressor rotor blades shrouds, as are used in turbines, are omitted.
As was mentioned before, rotor blades in a compressor have no shrouds available to them. Therefore, ends, or rather tips of the rotating rotor blades are exposed to a direct frictional contact with the housing in the case of so-called brushing against the stationary housing. Such a brushing of the tips of the rotor blades against the housing is brought about by the setting of a minimum radial gap by manufacturing tolerances. Since, on account of the frictional contact of the tips of the rotating rotor blades to the housing, material is eroded, it is possible for an undesired gap enlargement to set in over the entire circumference of housing and rotor. In order to avoid this, the ends or tips of the rotating rotor blades may be fortified with a hard coating or with abrasive particles.
Another possibility of avoiding the wear at the tips of the rotating rotor blades and of assuring an optimized sealing between the ends or tips of the rotating rotor blades and the stationary housing, is to coat the housing with a so-called run-in coating. In material removal on a run-in coating, the radial gap is not enlarged over the entire circumference, but only in the shape of a sickle, as a rule. This avoids a drop in performance of the engine. Certain housings having a run-in coating are conventional.